An electrophotographic image forming apparatus such as a copy machine and a printer includes an optical scanning device that emits light for forming an electrostatic latent image on a photoreceptor (for example, see Patent Literature 1). The optical scanning device has a box-like housing body opened upward and an upper lid that closes an upper side of the housing body. The housing body receives optical devices such as a light source, a polygon mirror, and an image forming lens. The upper lid is formed with an opening for leading optical beams emitted from the light source to an outer side of the housing body. The opening has a rectangular shape extending in a predetermined direction (for example, a main scanning direction) and is covered by a transparent cover such as a dustproof glass.
The upper lid is provided on the upper surface thereof with a cleaning mechanism for cleaning the dustproof glass. The cleaning mechanism has a cleaning member that abuts the surface of the dustproof glass and a driving mechanism that reciprocally drives the cleaning member in the predetermined direction along the dustproof glass. The driving mechanism has a screw shaft extending in the predetermined direction along the dustproof glass and an input gear that inputs rotational driving force to the screw shaft. The input gear is held to the upper lid via the screw shaft. There are cases where the input gear is directly held to the upper lid.
An image forming apparatus body is provided therein with a driving gear meshed with the input gear. The driving gear is disposed to be meshed with the input gear from below when the housing body is set in a predetermined place of the image forming apparatus body from above. The driving gear is connected to a motor provided in the image forming apparatus body. Rotation of the motor is transferred to the screw shaft via the driving gear and the input gear. By so doing, the screw shaft is rotated, so that a holding member is reciprocally driven along the dustproof glass and thus the surface of the dustproof glass is cleaned by the cleaning member.
At both sidewalls of the housing body in the predetermined direction, engaging projecting parts are formed to project outward from the housing body. The upper lid has a body plate part having a rectangular plate shape and convex parts projecting downward from parts corresponding to the engaging projecting parts at each side of the body plate part. The convex part is formed with a rectangular engagement hole. When the upper lid is mounted at the hosing body, the engagement holes are engaged with the engaging projecting parts of the housing body, so that the upper lid is fixed to the housing body.